An image forming apparatus such as a multi function peripheral (MFP), a copy machine, and a printer includes a fixing device for fixing a toner image transferred to a recording medium such as a recording sheet.
A fixing device often includes a fixing belt (circulating member for fixing) of which an annular peripheral wall circularly moves and a pressure roller (pressure member) that is pressed against the outer surface of the fixing belt. The pressure roller is driven to rotate by a driving device such as a motor. A nip for fixing is formed between the pressure roller and the fixing belt. A recording medium, such as a recording sheet, which is a fixing target, passes through the nip for fixing.
A pad material which presses the fixing belt from the inside thereof, a heater for heating the fixing belt, and a holding member which holds the pad material are arranged inside the fixing belt. The pressed surface of the pad material receives a pressurizing force of the pressure roller via the fixing belt.
As a fixing device in the related art, a fixing device generally includes a reflector for reflecting radiant heat of a heater toward a fixing belt. In this fixing device, radiant heat of the heater transferred in a direction of a member other than the fixing belt, such as a holding member, is blocked by the reflector. The radiant heat is reflected in a direction of the fixing member. As a result, the heating efficiency of the fixing belt by the heater is increased.
However, in the fixing device, some of the radiant heat emitted from the heater to the reflector heats up the reflector. As a result, the heat of the heated reflector is not used for heating the fixing belt and escapes to a member other than the fixing belt, such as a holding member. Therefore, it is desirable to have a fixing device capable of more efficiently heating a fixing belt.